Kokrajhar: Terror struck Assam on Friday when a group of heavily armed militants dressed in army fatigues and suspected of belonging to a Bodo separatist outfit opened indiscriminate fire and lobbed grenades at a crowded weekly market killing 14 people.

One of the attackers who were believed to be about five in number was killed in retaliatory action by security forces, police said.

Smoke rises after reported grenade attacks in the Kokhrajar area of Assam. Twitter @ANI_News

The police said that a group of heavily-armed militants, wearing army fatigues, came to the crowded weekly Balajan Tiniali market, about 12 km from here, in a van around noon and fired indiscriminately killing 12 persons on the spot and injuring more than 20 others.

Two other persons succumbed to their injuries enroute to the hospital, it added.

Prime Minister Narendra Modi strongly condemned the attack and said the Home Ministry is in touch with the Assam government.

"Saddened by the attack in Kokrajhar. We strongly condemn it. Thoughts & prayers with the bereaved families & those injured," he tweeted.

"The Home Ministry is in touch with the Assam Government & is monitoring the situation closely," Modi added.

The dead included a woman who was yet to be identified while six others have been identified as Mazhar Ali, Salam Ali, Danda Basumatary, Moniram Basumatary, Parmeswar Basumatary and Tapan Chakraborty.

Assam Director-General of Police Mukesh Sahay said the attack was suspected to be the handiwork of National Democratic Front of Bodoland (NDFB-S) and the operation was still continuing in the area. AK-56 and 47 series rifles along with grenades were also recovered from the spot.

Manik Debnath, a 30-year-old shop-keeper who was a witness to the mayhem, said that about five militants, wearing army uniforms and covering their faces arrived in a van and fired continuously, which continued for 15 to 20 minutes.

"A grenade was also lobbed by the militants which set on fire eight shops and screaming people began to run helter-skelter in a bid to escape," he said.

Assam Chief Minister Sarbananda Sonowal denounced the attack and said the militants would be dealt with "very sternly".

Sonowal, who is in Delhi, said the militants would be dealt with "very sternly", a statement from the CMO said.

"We will not tolerate any threat from any group. The government will not bow to any pressure while tackling terrorist groups," he said, adding all deputy commissioners and superintendents of police across the state have been directed to be on high alert following the attack and in view of the Independence Day.

He announced an ex-gratia payment of Rs five lakh to the next of kin of the dead, Rs one lakh to the seriously injured and Rs 20,000 to those who sustained minor injuries in the attack.

Describing the incident as "very unfortunate", Union minister of state for Home Kiren Rijiju said in New Delhi, "We have to ascertain who are exactly behind this dastardly act".

He said, "Peace had returned to the Bodoland area and this incident has given us shock. We will ensure that the victims families are taken care of".

Home Minister Rajnath Singh was briefed about the attack by National Security Advisor AK Doval.